How do I make a randomized order of the array modifier?
You can achieve this by using a Particle System. Simply add in a plane, go to the Particles tab, and follow the directions:


With the plane selected, add a new particle system by pressing New
Set the number of particles to something lower, like 10
Set the End frame to 1 (make sure the Start frame is also 1)


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Further down the settings:


Under the Physics tab, select No. This will turn off gravity.
Under the Render tab, set the emitter to Object, then by clicking the box, select the object you want to array/duplicate (in your case, the bubbles)


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Optional:


If you don't like the randomization of the particles, set the Seed
to a different number.


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You can hide the plane by putting it on a separate Render Layer or by assigning it an invisible material.

EDIT: You can also put the particles on a line by scaling down the plane on the Y axis. If you want it on a different axis, you can just rotate the plane. And finally, if you want it on a curve, simply just replace the plane with a curve.